Nebulization as a tool for photosensitizer delivery to the respiratory tract

Abstract

To this day, any photosensitizers for the photodynamic treatment of pulmonary illnesses have been administered intravenously. There is, however, an intrinsic difficulty in reaching the target cells or bacteria in the respiratory system. Nebulization could overcome distribution problems and alleviate side effects by delivering the photosensitizers directly to the lungs. In this study, we evaluated the viability of three photosensitizers (indocyanine green, the chlorine Photodithazine, and the porphyrin Photogem) was evaluated comparatively in a jet nebulizer. Quantitative analysis was performed by looking at the droplet size, extent of nebulization, output over time and stability of the solutions. All of the tested photosensitizers were found to be adequately nebulized. We also demonstrated the delivery of indocyanine green to the pulmonary tract and its activation with infrared light in a murine model using extracorporeal detection of fluorescence. This was an important step toward clinical implementation of the extracorporeally illuminated photodynamic inactivation of pneumonia, recently demonstrated in vivo by this research group.

Keywords: nebulization; photodynamic inactivation; photosensitizers; pulmonary delivery.